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[MarcRandolph <mrand@xxxxxxxxx>]

** Changed in: mythbuntu
       Status: New => Invalid

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[Lucid] Mythbuntu stalling with HDD light solid
https://bugs.launchpad.net/bugs/561601
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Status in Mythbuntu, Ubuntu derivative focused upon MythTV: Invalid

Bug description:
Hello all,

I've spent a long time trying to narrow this down, but I'm really struggling and could do with any help/suggestions that you can come up with.

I use an AMD 780G board with a 1TB Western Digital Green Power EAS HDD and a 2.4GHz (or thereabouts) Sempron (Sparta) LE-1200CPU. I have 2 GB RAM and have just added an nVidia 8600GT 512MB. I was previously using analogue TV over a pvr150 tuner and a bttv tuner. I have just replaced the pvr150 and bttv with a Hauppauge hvr-2200.

I have run Mythbuntu for quite a long time. We used 9.10 without too much trouble. At some point near the beginning of this year (I don't know what triggered it), Mythbuntu started stalling for 1-3 minutes at a time, with the hard disk light on solidly and nothing else working. The system would be virtually unresponsive, but would slowly crawl to a terminal etc. Then, after about 1-3 mins, it would be back to normal. I can't see anything that could be causing the problem in top, iotop or the system logs. It is very difficult as the issue causes a whole bunch of other issues in the logs (such as buffers filling up or kernel events timing out), making it hard to pick the symptoms from the cause. On a practical note, stalls during a recording often stop the recording taking place, which is pretty unhelpful for a PVR. In top there is often a very high percentage of "wa", which I understand means that a lot of things are waiting for I/O.

I have now changed the card to an nVidia and am using the proprietary drivers. I've replaced the tuner cards. I upgraded the system to Lucid Beta and downloaded all the latest updates. The problem is still occurring, even when all I was doing was browsing folders in Thunar.  To give an idea of the problem, running a 42 minute video in VLC took 53 mins with the stalls.  The memory looks okay (I have 2GB in it), with free -m showing most "used", but "cached".

On a few occasions when it has stalled, I have killed mythbackend (sudo stop mythtv-backend) and the system continues stalling for another couple of minutes. I had decided that the problem could be the hard drive itself, because I would get a lot of stalls whenever it was accessing the drive (such as when browsing in Firefox or copying files) so I tried to copy all of the files from the disk to an eSATA disk. I had also heard some rumours about issues with Green Power drives. Mythbuntu/Thunar said that this would take 42 hours for 200GB over eSATA (and seemed to be taking about that long for the first couple of hours or so — it initially said 7ish hours, then I set the ionice to BE7 so that it could do a recording, but it went up to 42 and didn't speed up after the recording finished), but rebooting to a live CD of Ubuntu Lucid Beta 2 did the job in 2 hours. This suggests to me that it isn't the disk, but that talking to the disk in Mythbuntu has issues that aren't in Ubuntu. I saw stalls in Mythbuntu before I configured it or imported my database, which makes me think that it is unlikely a corrupt database or similar. I'm struggling to think of anything that is different between Mythbuntu and Ubuntu that I haven't tested and eliminated as a cause.

Given that it isn't showing in top/iotop, I'm wondering if it is something really low-level. On the other hand, I would have thought it would need to be hardware/Mythbuntu-specific or everyone would be complaining. I've replaced most of the hardware that I thought could be causing the issues.

If anyone can help me, it would make a huge difference -- even if only to suggest more diagnostics or logs to review.

Thanks in advance,

Aaron